The present invention, in some embodiments thereof, relates to method and device of administering liquid medical substances and, more particularly, but not exclusively, to method and device of administering liquid medical substances in blood vessel.
Administration of liquid medical substances directly into venous lumen for treating blood vessels, for example for sclerotherapy, has been practiced for a number of years.
For example, sclerotherapy is used for eliminating large spider veins (telangiectasiae) and smaller varicose leg veins. The sclerosing solution closes the “feeder veins” under the skin that are causing the spider veins to form, thereby making a recurrence of the spider veins in the treated area less likely. Sclerotherapy can also be performed using sclerosants, such as microfoam sclerosants, under ultrasound guidance to treat larger varicose veins, including the great and small saphenous veins, see Paul Thibault, Sclerotherapy and Ultrasound-Guided Sclerotherapy, The Vein Book/editor, John J. Bergan, 2007, which is incorporated herein by reference. After a map of the patient's varicose veins is created using ultrasound, these veins are injected whilst real-time monitoring of the injections is undertaken, also using ultrasound. The sclerosant can be observed entering the vein, and further injections performed so that all the abnormal veins are treated. Follow-up ultrasound scans are used to confirm closure of the treated veins, and any residual varicose veins can be identified and treated.
One of the limitations sclerosing treatments for veins the concentration of the used sclerosing agents in certain target blood vessels. For example, some regulatory limitations restrict the concentration of sclerosing agents to less than 3% concentration if the target vein is less than 4 mm in diameter. In such concentrations, the sclerosing agent is rapidly diluted and therefore not sufficiently effective for treating the surrounding veins. Increasing the quantity and/or the concentration of the injected sclerosing agent to offset the dilution may introduce harmful quantities into the body.
It should be noted that foaming techniques have also been tried to treat veins using sclerosing agents. The delivering of sclerosing agents in a foam form at least partially offsets the effect of the sclerosant dilution. However, significant harmful effects resulting from the foamed sclerosants have been evidenced, in particular blood clotting throughout the vascular system, wherever the foamed sclerosant has reached.
Few devices and method have been developed for improving the administration of liquid medical substances, such as sclerosing agents, into the veins. For example, International Patent Application No. WO 2006/017470A2, published on 16 Feb. 2006, which is incorporated herein by reference describes a device and method for treating bodily diseases and/or conditions, for example, varicose veins, tumors and aneurisms including for example insertion of a blocking device toward a target destination using an intrabody device, such as a catheter, and delivery of sclerosing or other agents to the vessel while maintaining minimal, for example zero pressure in the treatment area. The blocking device may prevent treatment materials, embolisms, debris and the like from entering the upstream section of vessel. The blocking device may include, for example, a cap or other concave shape and may be expandable or extendible towards the vessel walls.